Development of the delamination evaluation parameters (I) — the delamination aspect ratio and the delamination shape factors —
Although the previous researches evaluated the fatigue behavior of A1/GFRP laminates using the traditional fracture mechanism, their researches were not sufficient to do it : the damage zone of A1/GFRP laminates was occurred at the delamination zone instead of the crack-metallic damages. Thus, previous researches were not applicable to the fatigue behavior of Al/GFRP laminates. The major purpose of this study was to evaluate delamination behavior using the relationship between crack length(a) and delamination width(b) in A1/GFRP laminate. The details of investigation were as follows : 1) Relationship between the crack length(a) and the delamination width(b), 2) Relationship between the delamination aspect ratio(b/a) and the delamination area rate ( (Ad)n/ (A d ) all) , 3) The effect of delamination aspect ratio(b/a) on the delamination shape factor (f s ) and the delamination growth rate (dA d /da). As results, it was known that the delamination aspect ratio(b/a) was decreased and the delamination area rate ( (A d ) n / (A d ) All ) was increased as the normalized crack size(a/W) was increased. And, the delamination shape factors (f s ) of the ellipse-II (f s3 ) was greater than of the ellipse-1 (f s2 ) but that of the triangle (fs1) was less than of the ellipse-I (f s2 ).
Key WordsDelamination Width(b) Delamination Aspect Ratio(b/a) Delamination Shape Factor (fs) Delamination Growth Rate (dAd/da) Delamination Area Rate ((Ad)n/(Ad)all) A1/GFRP Laminates Cyclic Bending Moment
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